1. Field of the Invention
The present invention relates to an optical component and an optical module using this component, which are used for optical communications and information processing.
2. Background Art
In the system of an access system, in recent years, a two-way communication system by a single core optical fiber has become a mainstream from among optical communications fields. In this case, a laser of wavelength of 1.49 μm or 1.55 μm is used from a center side to a subscriber, and a wavelength multiplexing transmission system (WDM, wavelength-division multiplexing) using a laser of 1.3 μm is utilized from the subscriber to the center side.
The optical module required for the above described system requires a semiconductor laser generating a laser of wavelength 1.49 μm or 1.55 μm, a light receiving element such as PD and the like receiving a laser of wavelength 1.3 μm, and a WDM filter circuit to separate both wavelengths at the center side. Further, at the subscriber side also, a semiconductor laser generating a laser of wavelength 1.3 μm, a light receiving element such as PD and the like receiving a laser of wavelength 1.49 μm or 1.55 μm, and a WDM filter circuit to separate both wavelengths are required.
For example, in the case of the single-core bidirectional module of a first type, a filter inclined to an optical axis is disposed at a fiber end, and from among the lights from the fiber end, the light of a target wavelength alone is reflected by a filter, and is guided to the light receiving element, while aligning it by a lens. On the other hand, the light from the semiconductor laser can be coupled to the fiber end through the filter, while being aligned by the lens (for example, The Institute of Electronics, Information and Communication Engineers, General Conference Preliminary Report Collection (2000), B-10-168, p543 [Coaxial Integrated Type ONU Optical Module for ATM-PON corresponding to descent 622 Mb/s]; The Institute of Electronics, Information and Communication Engineers, Electronics society General Conference Preliminary Report Collection (1996), C-208, p208 [Receptacle Type Two-Way Wavelength Multiplexing Optical Module 1]).
Further, the single-core bidirectional module of a second type, has a constitution in which an optical waveguide is coupled with the fiber end, and for this optical waveguide, an angle cut groove is processed by a dicing and the like, and a filter inclined to this groove is disposed. Here, from among the lights from the fiber end, the light of the target wavelength alone is reflected by the filter, and is guided to the light receiving element, and the light from the semiconductor laser disposed behind the filter is transmitted through the filter and the optical waveguide so as to be coupled with the fiber end (for example, Japanese Patent Application Laid-Open No. 2000-228555: The institute of Electronics, Information and Communication Engineers, Electronics Society Conference Preliminary Report Collection (1997), C-3-89, p198, [Surface Mounted LD/PD Integrated Module]).
Further, in the case of the single-core bidirectional module of a third type, the fiber end and the semiconductor laser are disposed respectively on a pair of V-character branched fiber ends by using a V-shaped PLC waveguide, and a filter is provided on the end face of the PLC waveguide corresponding to a V-character bottom, and the light receiving element is disposed oppositely to this filer. From among the lights from the fiber end, the light of the target wavelength alone is guided to the light receiving element through the filter by the end face of the PLC waveguide, and the light from the semiconductor laser is reflected by the filter provided on the end face of the PLC waveguide, and is coupled with the fiber end (for example, The Institute of Electronics, Information and Communication Engineers, General Conference Preliminary Report Collection (2000), C-3-132, p3128 [Development of 1.3 μm/1.55 μm-WDM Type PLC Module]; Oguro et al., “1.25 Gb/s WDM Bi Directional Transceiver Module Using with Spot-size Conversion Region”, 2002 Electronic Components and Technology Conference; The Institute of Electronics, Information and Communication Engineers, General Conference Preliminary Report Collection (2000), B-10-166, p541 [Preparation of Optical Transmitting and Receiving Module for ATM-PON OUN]; The Institute of Electronics, Information and Communication Engineers, General Conference Preliminary Report Collection (2000), C-3-129, p308 [Research Work on Low Crosstalk of Optical transmitting and Receiving Module for ATM-PON OUN]).
However, the optical module of the first type requires an aligning process to perform disposition adjustment of the lens and like, and skill and accuracy are required for the manufacturing of the optical module, thereby reducing yield ratio.
Further, while the optical module of the second type does not require an alignment of the lens and like since it uses the waveguide, after forming the waveguide, a groove process, and a process of insertion and adhesion of the filter are required, and this makes the manufacturing process of the optical module complicated.
Further, the optical module of the third type also requires a process of adhesion and the like of the filter in addition to the formation of the waveguide, and this makes the manufacturing process of the optical module complicated.